You're probably correct. It's a good example of the public interest in the security of suspects and the possibility of escape trumping my 4th amendment rights to walk around unsearched on public property. Like I said before, the cops don't need a good reason to prevent my access to prisoners, I need to present them with a good reason to be there. But they will need a reason to search my person in the front of the station.
What's been presented in the BWI case so far is no specific reason to search everyone. What that means to me is this is just more experiments at the BWI security lab. The security bureaucrats perform these experiments to test the acceptance of new security measures. Those who believe these searches materially improve security have passed the test.